Two-stroke engines provide the benefit of high power-output-to-weight ratios as compared to a four-stroke engine. This benefit results from the simplicity of operation of the two-stroke engine whereby exhaust of combustion gases from the cylinder and intake of fuel and air are executed simultaneously, such that each downward stroke of the piston is a power stroke. However, combining intake and exhaust in a single stroke creates the possibility that fuel will escape with the exhaust gases. This disadvantage has been reduced in part by injecting fuel directly into the cylinder of the engine. An engine control unit (ECU) typically controls the injection of fuel into the cylinder in order to avoid loss of fuel and to promote efficient combustion.
In a typical system, the ECU varies the amount of fuel injected based on such parameters as the throttle position or crankshaft velocity. However, these parameters do not provide a complete picture of the operating state of the engine as it affects fuel injection. Accordingly, such systems fail to capture improvements in fuel efficiency and emissions reduction that are available.
In view of the foregoing it would be an advancement in the art to more accurately measure the state of the engine insofar as it affects fuel injection and to use such measurements to tune fuel injection to improve fuel efficiency and reduce emissions.